ICUNTRIBUTIOh FROM THE AIASSACHUSETTS INSTITUTE OF TECHNOLOGY. LABORATORY OF ORGANIC CRBMISTRY. ]
THE ACTION OF SULFURIC ACID ON DICYANDIAMIDE.' BY TENNEY L. DAVIS Received January 17, 1921. It1 ib2.ti2 € h a g 2 found that dicyandiamide, .when boiled with acids, ombines with water to form a base which he called dicyan-diamidinc. 'jnd 13aumann in 187.1 showed3 that this base is guanylurea. I n 101:1 I,idholm4 studied the reaction, a t 80' and a t lOO', between equivalent quantities of dicyandiamide and 0.1 N sulfuric acid. He followed thr progress of the reaction by titrating the reaction mixture with methyl cxingc and alkali, a procedure which the strongly basic character of guanylurea made applicable, and calculated the reaction constant for the second order reactioa6 N H = C(NH2)NHCTS HzO + N H = C(NH2)NHCONHz. (I) The zame investigator found that strong sulfuric acid provokes the rapid e\-olution of carbon dioxide and carries the reaction further, converting the quanylurea into guanidine. XH == C(NH2)NH -- CO - NHz f HzO + NH = C(NHz)z COz "a. (11) Since these reactions provide a ready means of preparing guanidine from an abundant source, we have undertaken a study of them in an effort t u determine the conditions which will secure a maximum yield of product Under the conditions which are necessary for the formation of guanidine from dicyan-diamide, the primary reaction leading to the formation of guanylurea is very rapid while the other reaction leading to the formation of guanidine is relatively much slower-and it was believed that the progress of the reaction could be studied satisfactorily by confining thc attention merely to the rate of production of the products of the second and slower reaction. With 61% sulfuric acid a t 100' the production of guanidine is slow and a large amount of guanylurea survives after a heating of 6 hours. At higher temperatures the yield is better, and excellent yields can be obtained by 6 hours heating a t 140°, 160' or 200". -4t the high temperatures, a con-
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* The funds for this investigation were provided by a contract between the Or(!nance Department and the Massachusetts Institute of Technology, and the present paper is published by permission of the Chief of Ordnance. The experimental work was carried out by Anthony Contieri and James C. Vickery. 2 H a g , Ann., 122,22 (1862). 3 IBaumann, Bey., 7, 1760 (1874). Lidholm, ibid., 46, 156 (1913). * 'Se find that the same reaction occur< in d k J i n e solution, and are now studying tfir rnstter in this laboraton
670
TENNEY L.
DAVIS.
siderable increase of temperature produces only a slight increase in the amount of product, and the yields a t 140", a t 160' and a t 200" are essentially the same. At the higher temperatures more carbon dioxide is produced than the formation of guanidine requires, a result which indicates that guanidine itself is destroyed by the strong sulfuric acid, presumably in accordance with the following equation. NH = C(NH2)z 2Hz0 + COS 3NH3. (111)
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Discussion of Experiments. In the first experiments dicyandiamide was heated with 4 times its weight of 61% sulfuric acid and portions of the reaction mixture were removed a t intervals and analyzed for guanidine by precipitation with ammonium picrate according to the method of Vorzarik.' The precipitates were contaminated with varying amounts of guanylurea picrate, and results were erratic. Attempts to determine ammonia in portions of the reaction mixture were unsuccessful, for it was found that the alkali used to liberate the ammonia during the distillation process attacked the products of the reaction and caused falsely high results. Conditions were met by mesuring the rate of production of carbon dioxide. In a series of experiments, 8 g. of dicyandiamide and' 32 g. of 61% sulfuric acid were heated together in the apparatus illustrated in Fig. 1.
a Fig. 1.-Apparatus for studying rate of hydrolysis of dicyandiamide.
The temperature was maintained constant within 1" above or below. The Geissler bulbs were changed a t intervals of 30 minutes, and the carbon dioxide produced during the interval was weighed. At the end of Vorzarik, Z. angew. Chem., IS, 670 (1902).
ACTION O F
67 1
SULFURIC ACID ON DICYANDIAMIDE.
6 hours, guanidine in the reaction mixture was determined by the method of Vorzarik. The experimental data are given in the accompanying ta'ble. At 100'.
Half hour period.
At 120'.
P
At 140'.
c
.--A t 160'.
At 200'. I
During During During During During interval. Total. interval. Total. interval. Total. interval. Total. interval. Total,
First 0.1333 Second 0.1702 Third 0.1595 Fourth 0.1644 Firth 0.1525 Sixth 0.1500 Seventh 0.1450 Eighth 0.1304 Ninth 0.1207 Tenth 0.1104 Eleventh 0.0850 Twelfth 0.0405 Carbon dioxide, % of theory. Guanidine. by a.oalysis. Guanidine, o f theory.
0.1333 0.7734 0.3035 0.6013 0.4630 0.4394 0.6274 0.3291 0.7799 0.2367 0.9299 0.1867 1.0749 0.1445 1.1053 0.1210 1.2260 0.0923 1.3364 0.0762 1.4214 0.0544 1.4619 0.0617
34.8
0.7734 1.5220 1.5220 1.3747 0.8229 2.3449 1.8141 0.4717 2.8166 2.1432 0.2867 3.1033 2.3799 0.2080 3.3113 2.5666 0.1535 3.4648 2.7111 0.1055 3.5703 2.8321 0.0796 3.6459 2.9244 0.0670 3.7129 3.0006 0.0470 3.7599 3.0550 0.0442 3.8041 3.1167 0.0260 3.8301
74.5
1.97 35.1
3.84 68.3
91.3 4.76
84.7
1.7575 0.8615 0.4573 0.2793 0.1705 0.1138 0.0872 0.0550 0.0360 0.0255 0.0167 0.0105
1.7575 2.6190 3.0763 3.3556 3.5261 3.6399 3.7271 3.7821 3.8181 3.8436 3.8603 3.8708
92.4 4.80 85.4
2.1985 0.7260 0.3977 0.2253 0.1505 0.0877 0.0454 0.0391 0.0301 0.0184 0.0130 0.0090
2.1985 2.9245 3.3222 3.5475 3.6980 3.7857 3.8311 3.8702 3.9003 3.9187 3.9217 3.9307
93.8, 4.83 85.9
Fig. 2, the graph of these data shows that the variation in the amount o f produced carbonidioxide is remarkably regular, but the fact, brought out by the analysis, that the amount of carbon dioxide in certain cases is in excess of the amount of guanidine, probably renders impracticable the calculation of a velocity constant. 4.0 ai
P,
."0 3.0 0
-e 2i
% 2.0
8 1.0
0
Fig. 2.-Rate
1
2 3 4 5 Duration of heating-hours. of production of carbon dioxide from dicyandiamide by heating with 61% sulfuric acid.
(172
~ o r c. r ~i i E s s , m
IVILLIAM P . HCSDERSOA
In the 100" run the apparent amount of guanidine as indicated by analysis is larger than that which corresponds to the amount of carbon dioxide, a result which can lead only to the inference that the precipitated picrate was contaminated with picrate of guanylurea and to the conclusion that the figure for carbon dioxide is probably fairly representative of t t i c x t u a l amount of guanidine. In the other runs a t higher temperaturq tlie cxboti dioxide exceeds the guanidine. But the reactions (I1 and I1 I ,ibove) which lead to the formation of guanidine and to the destructioii ( i f guanidine each produce onc mol-equivalent of carbon dioxide. '1'11~ ctrttial amount of guanidine, therefore, which is produced during thc 1-caction (and in part destroyed) is represented by the arithmetical mcail between the value given by analysis and that indicated by the carbon dioxide. nicyandiamide heated for 6 hours with 4 times its weight o t 617' sulfuric acid actually produces a t 100' about 3 3 . S s ; a t 120', 71. I C c , a t 140°, S S . O z ; a t 160", 88.9% and at %O0, 89.95 of the theoretical xnount of guanidine. C A M B R I D C C , hfASSACHLSLl'rS.
[CONTRIBUTIOS 1)ROY THE ~ f E I , L O NINSTITUTE OF IhPUSTRLAL YERSITY OF
RESEARCH OF THE
\ I-
PITTSBURGH ]
BUTYL- AND ISOBUTYL-CYANO-ACETIC ACIDS.' RY
JOHN
C. HESSLERAND WILLIAXF. HENDERSON. Received January 17, 1921.
In continuation of the work already done on the alkylation of cyanoacetic acid ethyl ester, the authors have carried out the Conrad-Limpach reaction with iso-butyl alcohol as the solvent and have determined that the iso-butyl and di-iso-butylcyano-acetic esters formed were iso-bz4t31 esters rather than ethyl esters. The present paper also describes a numbrr of salts of iso-butyl and di-iso-butyl-cyano-aceticacids, as well as the preparation of noniial butyl-cyano-acetic acid and ester and a number v i their derivatives. I. Action of Cyano-acetic Acid Ethyl Ester with Sodium Iso-Butylate and Iso-Butyl Iodide in Iso-Butyl Alcoholic Solution.-A solution of sodium iso-butylate was prepared from 6.6 g. of sodium and 185 cc. of absolute iso-butyl alcohol. The solution solidified when cold. It ~ i ' a i treated with 32.4 g. of cyano-acetic acid ethyl ester dissolved in 65 cc. of absolute iso-butyl alcohol, and the mixture was warmed slightly until the solid sodium salt went into solution. The solution was then cooled and 53 g. of iso-butyl iodide was added. This is an excess of 2 g. The solution gradually assumed a deep-red color. -4fte.r 40 hours the iolution was heated to boiling until it was neutral to litmus. The isoMost of the work described in this paper was carried out in the Chemical 1 ~ 1 ) oratory of the James Millikin T'niversity
